The main specific application of the invention is making such cases, or boxes, or other volumes which are insulating for the purpose of transporting or storing merchandise that need to be maintained at a temperature that is as stable as possible, in particular for small quantities of merchandise that are sensitive to extremes of temperature and to sudden changes of temperature, such as foodstuffs, pharmaceuticals, chemicals, etc. . . . .
One of the main applications of the invention is assembling such cases or boxes or other volumes which are self-supporting, stackable, and suitable for handling on pallets by forklift handling equipment.
Such foldable cases or boxes are known for transporting all types of merchandise, but without seeking to provide thermal insulation, and they are therefore unsuitable for the above purpose unless insulating panels are added to the insides of the walls once they have been assembled to create a packaging volume, thereby increasing the number of components required for building such a volume, complicating assembly, increasing the folded volume of the kit, and naturally also increasing its weight which is disadvantageous for transportation by air, and also decreasing the volume available for packaging, which makes such cases expensive.
In the field of foldable boxes and cases for packaging and transportation purposes, various patent applications are to be found, in particular for solving problems either to do with strength to enable them to be stacked, or else to do with manufacture, to reduce costs and to simplify assembly by optimizing the cutting out of mutually folding walls as well as possible. By way of example, to achieve the first objective, mention may be made of French patent application 2 654 703 published on May 24, 1991 in the name of ECOPAL for a "foldable pallet case". For that purpose, that document describes a rectangular pallet made essentially of wood, supporting a skirt which, in the deployed state, is in the form of a rectangular parallelepiped having open bottom and top faces, and in which each of two opposite transverse faces has a respective vertical fold line substantially in the middle subdividing it into two half-faces, thereby enabling said skirt to be folded concertina-like, and such as to enable it to be provided with two stiffening elements of shape and size corresponding substantially to the shape and size of said foldable transverse faces. Since the elements are fixed to the inside of the skirt, each to one of the two half-faces of the two transverse faces, they do indeed ensure that the pallet case is self-supporting and strong enough for them to be stacked with other such cases, while nevertheless making it possible for it to occupy a small volume once folded, given the ability of the kit to be disassembled and folded. Nevertheless, because the skirt is disposed as a continuous belt and includes two rigid elements on the insides of its foldable walls, the range of dimensions that are possible for the case is limited. Also, that disposition does not enable the other two faces also to be strong enough to be self-supporting, since that would not enable the set of side faces to hold together nor would it guarantee stability for the case as a whole. Furthermore, if it desired for such a foldable pallet case to be insulating, then it is still necessary to add pre-cut insulating elements inside it.
Mention may also be made of French patent 2 535 288 published on May 4, 1984, and filed by PAPETERIE LEON CLERGEAU and L'HEXAGONE, entitled "foldable self-supporting case for packaging and transport purposes and usable as a display unit". That document describes a foldable case in the shape of a rectangular parallelepiped, which case is constituted by a preassembled web comprising a single card blank made of a material having good mechanical strength, with cutouts and folds making it possible, on setting up its volume, to obtain a bottom and two opposite side walls of the package, each having lateral strips coming back at right angles for the purpose of stiffening the corners formed, with connections between the strips being provided by tongues that are fixed by adhesive. The side walls are held in the unfolded position by installing one or both of the other side walls that are continuous and received in the angles of the two opposite unfolded walls. The base element may be fitted with studs or wooden bars of thickness and spacing determined to enable the package to be handled by a forklift truck, and if it is desired to improve the stacking strength of the package, the strength of each of the angles is increased by the presence of return-forming strips serving to line the corner in each angle of the package.
The objective of that second patent is above all to solve a manufacturing problem by minimal cutting of a single base sheet of card, and to make it possible to provide a package that is capable of serving as a display unit. However in that case also, if it is desired to obtain an insulating package, it is necessary to add elements to the inside thereof. In addition, its suitability for stacking with other packages is rather limited, since it has no genuinely stiff element other than the corner angles for supporting heavy loads.
It can thus be seen that for each particular application, and depending on the specific problem posed, it is necessary to develop a folding system adapted thereto, and at present there exists no such system suitable for making directly an insulating box that is foldable and of sufficient strength, without any need to add additional panels for that purpose inside a standard volume.